Defroster



Sept. 2, 1952 M- M. SCHULTZ DEFROSTER Filed Sept. 29, 1948 2 SHEETS-SHEET 1 v/w?7zE 4. 50/04 r-z,

P 1952 M. M. SCHULTZ 2,609,472

DEFRQSTER Filed Sept. 29, 1948 2 SHEETS-SHEET 2 rig WYATZE Vfl 5041/4 7-2,

-- 3% M r/m4 62%) Patented Sept. 2, 1952 DEFROSTER Myrtle M. Schultz, Texarkana, Aria, assignor, by direct and mesne assignments, of six-tenths to C. B. Schultz, Miller County, Ark., and onetenth to BryanBlalock, Texarkana, Ten, and three-tenths to. Thomas B. Westbrook, Smith County; Tex.

Application September 29, 1948; Serial No. 51,810

4 Claims. 1;

This invention relates to a defroster, and more particularly to an electrically operated defroster adapted to be inserted into a freezing compartment of a mechanical refrigerator for effectively defrosting the freezing unit.

Heretofore the defrosting of mechanical refrigerator freezing units has been more or less tedious because of the] time element involved and becausev of. the close attention. required to avoid flooding of the refrigerator by water resulting from th melting of, ice. and frost about the fteezingunit.

It is, thereforaan object of thisinvention to provide a device and amode, for its use, with which even. a heavily frosted freezing unit. may be completely and thoroughly defrosted in. a. matter of minutes and without any. resultant flooding of the refrigerator. compartment.

The objects of the inventionare. attained by providing an electric heater, which. is adapted. to

be inserted into a freezing compartment. of a freezing unit, in conjunction with a. heat, retaining: bag adapted to envelop the entire,.freezing unit, which retainer at the same time, being water-proof, forms a receptacle for. drippage of frost, ice and water.

The nature of the, invention will be more,

clearly understood as the specific description thereof proceeds with, reference to the accompanying. drawings forming apart of thisapplication, and in which drawings Figure l is an elevational' View of amechanical refrigerator showing, the device in position.

to achieve the defrosting of the freezing. unit.

Figure, 2 is a perspective, view of the electric.

heater forming an important part. of the inven-v It is an important feature of the invention to provide means for inducing a circulation of air about the heating device and about the freezing unit which is being defrosted. Ordinarily, an electric heating tool providing no special means for circulating the air during the defrosting operation would prove unsatisfactory for the purpose. It is, therefore, one of the principal objects of this invention to provide in the heat ing tool herein special means for circulating the, air and inducing a circulation thereof, Ac-- cordingly, the heater includes an open ended In its more specific aspect, the base structure It is composed of a tray 26, which has upstand-- ing side walls 28 and an open top. The tray 26 has nested therein an insulating tray 30. The tray 30' includes a transverse partition 32, which divides the same into a major compartment 34 and a minor compartment 3.6. Within the major compartment at is disposed an electric heating device mounted on a base member 38, and this device consists of a conventional resistance coil Mland a thermostatic switch 42, together with the necessary leads for making an electric connection with an extension cord.

Thepartition 32 has provided therein a notch, which opens through theupper edge of said par-- tition, this notch being provided as a passage for the heater leadsM. The heater leads 44 are Joined to the extension cord leads 46. within, theminor compartment 36, and this compartmentmay then be packed with insulating material. The extension cord 655 is adapted to pass outwardly through an upwardly opening'notch in the endwall of the minor compartment and through the manipulating handle of the device.

The base member also includes a cover 59, which has side walls 52 of substantially greater depth than the side walls 28 of the tray 26; As;

The arcuate.

a result of this structure, the tray 26 and the cover 50 may be completely telescoped whereby the free edges of the cover side walls 52 form supports for the base structure and the lower face of the tray 26 is held in an elevated position.

It will be noted that the side walls of the arcuate heat deflector 20 extend downwardly, so that a through fastening device, such as the bolt 54, may be passed through the side walls of the deflector and the side walls of the cover member at a point below the lower face of the tray 26, whereby the base and the deflector are held in assembled position, the bolt 54 serving to support the tray 26 in its fully telescoped position within the cover 50.

It is contemplated that the defrosting device be used in connection with a flexible waterproof bag 56, which is adapted to envelope the freezing unit of the refrigerator. The bag 56 is preferably transparent, so that the progress of the defrosting operation may be observed. The bag 56 is provided at its open end with a draw string 58 or an elastic band to facilitate its adjustment in substantially closed position about the freezing unit.

The thermostatic switch 42 is preferably preset at an optimum point found to be the most effective for defrosting purposes, and the switch is of such nature as to keep the heating element at a substantially constant temperature.

I In use of the device, therefore, the ice trays are removed from the freezing compartments and the electric heater is inserted into one of the compartments, usually the larger bottom compartment of the tier, and the flexible water-proof sack 56 is then adjusted and closed about the freezing unit l2. The extension cord 60 extends from the nearly closed top of the flexible sack 56 and may be connected with any suitable source of electric current. The door of the refrigerator may then be substantially closed and upon operation of the heating unit [0, the heated currents circulate with some degree of turbulence through the open ended arcuate heat deflector 20, through the side apertures 22 thereof, and through the circulation passages 24 under the base of the heater. It is to be noted herein that an insulating strip 60 is provided longitudinally in the top of the deflector 20, thereby avoiding undue localized heating of the freezing compartment in which the heater is positioned. The circulation of heated air that is induced by the described circulating passages effectively elevates the temperature within the flexible sack 56 and the defrosting operation is completed in a very short period of time.

The flexible sack 56 serves not only as a heat retaining instrumentality, but also serves the important purpose of holding pieces of frost and ice, as well as water, that drop from the freezing unit whilethe heater is in operation. Thus, the defrosting operation may be observed through the transparent walls of the sack 56, and upon completion thereof the current may be discontinued, the sack may be removed and emptied, and the heater may be withdrawn from the freezing compartment.

Because of the relative short time that is required for the defrosting operation, and because of the fact that the sack 56 provides a heat insulating wall between the atmosphere within and the atmosphere in the food compartment of the refrigerator, the overall temperature of the refrigerator is not materially lowered during the defrosting operation. Furthermore, since the operation is a rapid one, and since the temperature within the food compartment of the refrigerator is not substantially lowered, the refrosting of the freezing unit follows promptly upon removal of the defrosting gear. The refrosting is also facilitated because the normal operation of the freezing equipment need not be disabled during the defrosting period.

The invention has been described in a preferred operative form, but modification may be made in its structure and operation within the scope of the claims.

I claim:

1. In a defroster, a base tray for receiving a heating unit, a second tray of heat insulating material nested in said base tray, a transverse partition in said second tray dividing the same into a major compartment and a minor compartment, an electric heater in said major compartment, heater leads extending through said partition and being connected in said minor compartment to an electric cord, and a telescopic cover for said base tray, said cover having side walls exceeding in depth the side walls of said tray, fastening means for securing said base tray adjacent to the upper portion of said cover whereby the lower face of said tray is held above a supporting surface by said walls.

2. A defroster adapted to be inserted into the freezing compartment of a refrigerator comprising a rectangular base structure for enclosing a heating unit, an electric heater in said base structure, an open ended arcuate heat deflector arranged longitudinally above and extending over said base structure, a strip ,of heat insulating material fixed to the under surface, of said deflector, a pair of oppositely disposed air passages in the longitudinal side walls of said deflector at least a portion of which extends above the upper face of said base structure providing a transverse air passage, means for supporting said base structure with the lower face thereof above a supporting surface, and a pair of oppositely disposed passages under said base for inducing circulation of air about said defroster. 3. In a defroster, a base tray for receiving a heating unit, a second tray of heat insulating material nested in said base tray, a transverse partition in said second tray dividing the same into a major compartment and a minor compartment, an electric heater in said major compartment, heater leads extending through said partition and being connected in said minor compartment to an electric cord, and a telescopic cover for said base tray, said cover having side walls exceeding in depth the side walls of said tray, fastening means for securing said base tray adjacent to the upper portion of said cover, whereby the-lower face of' said tray is held above a supporting surface by said walls, and an open ended arcuate heat deflector arranged above an extending over said base structure.

4. In a rectangular defroster adapted to be inserted into the freezing compartment of a refrigerator, a base tray having upstanding side walls for receiving a heating unit, a telescopic cover for said base tray, said cover having side walls exceeding in depth the side walls of said tray, whereby the lower face of said tray is held above a supporting surface by said walls, an open ended arcuate heat deflector arranged longitudinally above and extending over said cover, a pair of oppositely disposed air passages in the side walls of said deflector at least a portion of 5 which extends above the upper face of said cover, a plurality of air passages in the side walls of said cover at a point below the lower face of said tray, fastening means extending through the side walls of said deflector and cover and underlying and supporting said tray and an electric heating unit in said base.

MYRTLE M. SCHULTZ.

REFERENCES CITED The following references are of record in the file of this patent:

Number 6 UNITED STATES PATENTS Name Date Hadaway, Jr Mar. 26, 1901 Beers June 24, 1913 Pruden Mar. 10, 1925 Brandstetter June 15, 1926 Roach Apr. 5, 1949 

